Cornstarch Monsters – Sick Science!
An awesome visualization of sound waves and frequency using oobleck
If you’ve ever watched an action movie in a theater, you’ve seen and felt an onscreen explosion. Did you know that what you were feeling was actually waves of sound from the theater’s speaker system? We’ll show you how you can visualize the sound vibrations and explain why, even though you can’t always see it, you can feel sound. Click here to download the sample tone.
- Garbage bag or plastic wrap
- One box of cornstarch (16 oz)
- Large mixing bowl
- Pitcher of water
- Gallon size zipper-lock bag
- Newspaper or a plastic drip cloth to cover the floor
- Download the audio sample we used
- Pour approximately 1/4 of the box of cornstarch into the mixing bowl and slowly add about 1/2 cup of water. Stir. Sometimes it is easier to mix the cornstarch and water with your bare hands–of course, this only adds to the fun.
- Continue adding cornstarch and water in small amounts until you get a mixture that has the consistency of honey. It may take a little work to get the consistency just right, but you will eventually end up mixing one box of cornstarch with roughly 1 to 2 cups of water. The mixture gets thicker or more viscous as you add more cornstarch.
- Notice how the substance is neither 100% solid nor 100% liquid.
- Gently lay your speaker on its back so that the speaker faces upwards. Make sure that your sound system is off.
- Cover the speaker with thin plastic like a trashbag or plastic wrap.
- Pour the non-Newtonian liquid onto the plastic on top of the speaker cone.
- Turn on your sound system and turn up the volume. Pick a track that has a low, consistent bassline and press play. (You can also download the audio track that we use.). Watch the non-Newtonian fluid. What’s happening?
- Try different tracks to see which track works the best. Which one is it?
- Do low or high sounds have more of an effect on the non-Newtonian fluid?
How Does It Work?
You probably noticed that lower frequencies (the sounds of an explosion or bass in a song) subjected the oobleck to much more movement. Knowledge about sound waves, however, might lead you to believe that it should be the exact opposite. The higher pitched sounds have a higher frequency (meaning there are more vibrations per second). But more vibrations don’t equal more movement of the non-Newtonian fluid. Instead, it is the lower pitched (lower frequency) sounds that cause the oobleck to shake. Although there are fewer vibrations per second at lower pitches, these frequencies cause more motion in the speaker cones.
For more information on oobleck, the non-Newtonian fluid, check out this experiment: Non-Newtonian Cornstarch Recipe.